Explosive actuated switch in whitch contact pierces nonconductor



March 1, 1966 R. c. LAWWILL ETAL EXPLOSIVE A H 3,238,321 CTUATED SWITCIN WHICH CONTACT PIERCES NON-CONDUCTOR 2 Sheets-Sheet 1 Filed May 15,1964 IN VEN TORS A iTOR/VE Y March 1, 1966 R. c. LAWWILL ETAL 3,233,321EXPLOSIVE ACTUATED SWITCH IN WHICH CONTACT PIERCES NON-CONDUCTOR FiledMay 13, 1964 2 Sheets-Sheet 2 32 Q l/ N 2 jbs \4 u 5 F g. 5

RON/4L0 c. LAWW/LL Fl 4 HAROLD L. ANDERSON INVENTORS ATTORNEY UnitedStates Patent 3 238,321 EXPLOSIVE ACTUATIiD SWITCH IN WHICH CON- TACTPIERCES NONCONDUCTOR Ronald C. Lawwill and Harold L. Anderson,Albuquerque, N. Mex., assignors, by mesne assignments, to the UnitedStates of America as represented by the United States Atomic EnergyCommission Filed May 13, 1964, Ser. No. 367,263 7 Claims. (Ci.ZOO-61.08)

The present invention relates generally to electric switches and moreparticularly to a fast acting switch for transferring electrical energywith high eificiency.

The invention aims to provide improved switches or circuit cont-rollingmeans of fast action, relatively simple construction and operation,small size, high reliability and high efiiciency.

An object of the present invention is to provide new and improvedelectrical switch means.

Another object of the invention is to provide a switch for transferringelectrical energy with maximum efficiency.

Another object of the invention is to provide an improved fast actionswitch of high reliability and relatively simple construction andoperation.

A further object of the invention is to provide improved switch meansthat may be readily manufactured by employing injection moldingtechniques to form synthetic resin molding material about conductingelements.

Other and further objects of the invention will be obvious upon anunderstanding of the illustrative embodiment about to be described, orwill be indicated in the appended claims, and various advantages notreferred to herein will occur to one skilled in the art upon employmentof the invention in practice.

A preferred embodiment of the invention has been chosen for purposes ofillustration and description. The preferred embodiment illustrated isnot intended to be exhaustive nor to limit the invention to the preciseform disclosed. It is chosen and described in order to best explain theprinciples of the invention and their application in practical use tothereby enable others skilled in the art to best utilize the inventionin various embodiments and modifications as are best adapted to theparticular use contemplated.

In the accompanying drawings:

FIG. 1 is a sectional view through one form of the present switch means;

FIG. 2 is a top plan view of the device shown in FIG. 1;

FIG. 3 is a horizontal sectional view taken generally along line 33 ofthe device of FIG. 1;

FIG. 4 is an enlarged fragmentary sectional View of one form ofexplosive actuator and plunger construction; and

FIG. 5 is an enlarged fragmentary sectional view showing a portion ofthe switch subsequent to actuation.

Described generally the present switch may comprise a first terminal oranvil 1 spaced from terminal means 2 and separatedtherefrom by solidinsulating material 4, with the terminal means 2 carrying tubularportions 5 each of which houses a movable plunger 6. An explosiveactuator 7 serves to drive the plunger 6 along the tubular portion 5 andthrough the insulating material 4 at an appropriate instant, so as tobridge the space between terminal means 2 and first terminal 1 andestablish electrical continuity between the first terminal and theterminal means.

In more detail, the switch is shown to comprise a first terminal oranvil ll of appreciable mass electrically isolated by a barrier ofmolded plastic material 4 and a layer of insulating material 8 from aterminal means 2. The first terminal and terminal means may each be ofsome durable and good electrically conducting material, such as brass orthe like. In the illustrated embodiment one or more conductors (notshown) may be coupled in any suitable manner with the first terminal 1,e.g., by the illustrated threaded connection 10, and one or more otherconductors (not shown) may be coupled with the exposed flange 2a of theterminal means 2 e.g., by wires inserted into the apertures 11 andthereafter soldered into position. In un-actuated condition, noelectrical path exists between the first terminal 1 and the terminalmeans 2, which are electrically isolated from each other by the moldedmaterial 4 and insulating layer 8. At a desired instant electricalinterconnection may be established between the first terminal 1 and theterminal means 2 by one or more of the connecting plungers 6, which movefrom the positions illustrated in FIGS. 1 through 4 to interconnectingor actuated positions such as shown in FIG. 5, in response to impellingforce provided by the explosive actuators 7.

Terminal means 2 is shown provided with four pockets lined with themolded material 4 and having apertures 13 therethrough, into each ofwhich is press-fitted a plungerguiding tubular member or bushing 5 sothat a shoulder 14 abuts an adjacent surface of the terminal means 2. ItWill be noted that the shoulder 14 is formed with what may be termed areverse slope or angle, for a purpose which will be hereinafterdescribed. Into each of the tubular members 5, preferably of brass orthe like, is press-fitted a movable steel plunger 6, the plunger beingof relatively small mass to facilitate movement under the influence ofpressure or shock wave supplied by the actuator 7. Under normal orun-actuated conditions the base or rear surface of the plunger issubstantially flush with the base surface of the tubular member 5, asillustrated more particularly in FIG. 4.

Any satisfactory degree of firm press fit may be employed between theexterior of the tubular member 5 and the aperture walls 13 into which itis fitted, and between the plunger 6 and the tubular bore of the member5 into which it is fitted. An appreciation of the small size and mass ofthe plunger may be obtained when it is realized that in actual usage,its base or cylindrical portion may have a diameter of about .06 inch,overall length of around .14 inch, with a tapering forward portion ofaround 30. The front end of the plunger is preferably not sharplypointed but somewhat blunted as generally indicated, to thereby minimizeobjectionable breaking off of the plunger tip. The reverse angle on theshoulder of the tubular portion 5 may be in the neighborhood of about15.

Movement of plungers 6 to interconnecting positions, such as in FIG. 5,may be achieved by explosive actuators 7, shown resting against andsubstantially flush with the tubular members 5 and the plungers 6 andelectrically isolated therefrom by insulator cups 15 of suitable plasticinsulating material, e.g., a thin (about .005 inch) film of polyethyleneterephthalate (Mylar). The insulator cups need not be adhesively securedto the explosive actuators but may be merely fitted thereover asindicated. Each actuator may comprise (FIG. 4) a flanged steel shell 19containing a quantity of quick-acting explosive material 24 such as amixture of lead azide and lead styphnate, and housing an electricalcontact assembly of Kovar tube 20, Kovar terminal pin 21 separated fromthe tube 20 by insulating glass 22, and bridging wire 23 interconnectingthe terminal pin 21 and tube 20. The flanges of the tube 20 and shell 19may be joined together by any suitable solder or conducting bondingmaterial, and the joined flanges electrically connected by solder 25with individual brass terminal members 26, from the latter of whichproject conducting terminal pins 27 of steel, brass, or the like.

Each explosive actuator and its terminal pin 21 is electrically isolatedfrom the others and each may, if desired, be hooked-up in such manner(not shown) as to respond to a different external event or selection.Also, if desired, two or more actuators may be coupled together inparallel arrangement to an external hook-up so as to simultaneously firethe actuators in response to an external event or selection. Actuationof two or more actuators coupled in parallel affords increasedreliability by insuring that at least one of the paralleled actuatorsilfiresl As will be clear more particularly from FIGS. 1, 2 and 5,firing of an explosive actuator may be achieved by current passing, forexample, through terminal pin 21, across bridge wire 23, through shell19 and tube 20, across brass terminal member 26, and thence through aconducting terminal pin 27 which may be secured to the terminal memberin any suitable manner such as soldering, pressed-fit, etc. When currentreaches a bridge wire 23 the explosive material 24 is initiated to exertforce against the flush ends of both a plunger 6 and tubular portion 5.As a result a plunger moves with great rapidity to penetrate theisolating synthetic resin material 4 and insulating layer 8 andpenetrate partially into the first terminal or anvil 1. The actuatedplunger 6 spans the distance between the previously isolated terminalsso as to now electrically interconnect them.

As a plunger moves through a tubular portion 5, force exerted on thebase end of the tubular portion tends to swing or fulcrum the upper partof the tubular portion inwardly about the contacting rim of the shoulder14 so as to decrease the cross sectional dimension of the bore behindthe moving plunger 6, thus tending to minimize or prevent objectionablerebounding or bouncing of the plunger back up the bore subsequent tostriking the first terminal or anvil 1.

The relatively thin (about .005 inch) layer or film of insulatingsynthetic resin material 8 over the terminal 1, which film may bepolyethylene terephthalate and preferably secured in position by somesuitable adhesive, provides a very desirable feature. In some instancesthe electrically isolating and encapsulating material 4 between thefirst terminal 1 and terminal means 2 tends to crack or break apart,thus creating objectionable arcing paths between the two terminals. Ithas been found that the noted thin film or layer 8 over the firstterminal 1 prevents such cracks from penetrating entirely through to theterminal 1 and hence if any cracks or breaks occur such do not gothrough the film or layer 8 and the latter continues to provideeffective electrical insulation except at the location of penetration bya plunger 6.

In manufacturing the switches, the first terminal or anvil 1 (withinsulating layer 8 adhered thereto), the terminal means 2, and theterminal members 26 may be positioned and retained in any suitable moldand suitable synthetic resin molding material injected under pressureinto the mold to firmly embed and encapsulate the noted elements ormembers therein. Diallyl phthalate has been found very satisfactory forthe molding material. The upper recess 31 (FIG. 1) and recesses 32 forreceiving the tubular members 5 and explosive actuators 7 may be formedin connection with the injection molding operation or, for example, onlythe upper recess 31 may be so formed and the other recesses 32 formed bysubsequent drilling operations. For insuring good electrical contactcare should be exercised to see that metal to metal contact is obtainedbetween each of the tubular members 5 and adjacent portions of theterminal means 2.

It will be noted (FIGS. 1 and 2) that the insulating and encapsulatingmaterial 4 is shown provided with recesses or cut-outs 28 at aboutintervals around the periphery of the switch, a recess being disposedintermediate each of adjacent terminal members 26. This feature furthercontributes toward optimum operation and reliability in that if aparticular explosive actuator were, during firing, to exertobjectionable or excessive lateral force tending to tear the switchapart, such objectionable force tends to be relieved or vented so thatthe quadrant with such actuator merely tends to separate itself from theremainder of the switch, without interfering with the remainder of theswitch. For example, if one actuator of a pair of diametrically oppositeactuators coupled in parallel for reliability in firing were to exertobjectionable lateral or sidewise force, the quadrant with theobjectionable actuator would separate itself from the switch but leavethe diametrically opposite quadrant with its actuator free to operateits plunger and effectively close a circuit.

It will be seen that the present invention provides new and improvedfast acting switch means of relatively simple and compact constructionwhich is well adapted to hold off a wide range of voltages but torapidly close when desired and transfer electrical energy with maximumefficiency. The compactness of the switch may be appreciated when it isrealized that its overall dimensions may be only about one inch inlength and diameter.

As various changes may be made in the form, construction and arrangementof parts herein without departing from the spirit and scope of theinvention and without sacrificing any of its advantages, it is to beunderstood that all matter herein is to be interpreted as illustrativeand not in a limiting sense.

We claim:

1. In an explosive actuated switch in which a contact pierces anonconductor, the combination of a first electrically conductingterminal, electrically conducting terminal means spaced from said firstterminal, a recess in said terminal means, a radially inwardlydeformable tubular portion in said recess having an opening therethroughin alignment with said first terminal, an electrically conductingmovable plunger carried by said tubular portion within said openingadapted to electrically interconnect said first terminal and saidterminal means when the switch is actuated, solid insulating materialnormally filling the space between said first terminal and said terminalmeans, and plunger actuating means disposed in said recess axially withand in a contiguously abutting relationship and substantially overlyingthe tubular portion and the plunger.

2. The device of claim 1 in which the tubular portion is radially spacedfrom the recess and is supported on the terminal means by a contactingrim adjacent the wall of the recess.

3. The device of claim 2 in which the tubular portion deforms radiallyinwardly about the contacting rim so as to decrease the cross sectionaldimension of the opening behind the plunger upon actuation of theswitch.

4. The device of claim 1 in which a layer of insulating material closelyoverlies said first terminal at a surface thereof disposed toward saidplunger.

5. The device of claim 1 in which the plunger has a tapering portiondisposed toward said first terminal and the extremity thereof is ofblunted configuration.

6. The device of claim 1 in which a layer of insulating material isdisposed intermediate the plunger actuating means and the terminalmeans.

5 6 7. The device of claim 1 in which the solid insulating FOREIGNPATENTS material is provided with a plurality of recesses in spaced 921463 1/1947 France relationship at the periphery of said switch adaptedto 1291058 3/1962 France relieve objectionable lateral forces duringactuation of Said Switch 5 BERNARD A. GILHEANY, Primary Examiner.

R f ren it by the Examiner I T. MAcBLAIN Assistant Examiner.

UNITED STATES PATENTS 2,816,196 12/1957 Daudelin 200 142 3,155,87611/1964 Paul 200-61.08 1O

1. IN AN EXPLOSIVE ACTUATED SWITCH IN WHICH A CONTACT PIERCES ANONCONDUCTOR, THE COMBINATION OF A FIRST ELECTRICALLY CONDUCTINGTERMINAL, ELECTRICALLY CONDUCTING TERMINAL MEANS SPACED FROM SAID FIRSTTERMINAL, A RECESS IN SAID TERMINAL MEANS, A RADIALLY INWARDLYDEFORMABLE TUBULAR PORTION IN SAID RECESS HAVING AN OPENING THERETHROUGHIN ALIGNMENT WITH SAID FIRST TERMINAL, AN ELECTRICALLY CONDUCTINGMOVABLE PLUNGER CARRIED BY SAID TUBULAR PORTION WITHIN SAID OPENINGADAPTED TO ELECTRICALLY INTERCONNECT SAID FIRST TERMINAL AND SAIDTERMINAL MEANS WHEN THE SWITCH IS ACTUATED, SOLID INSULTAING MATERIALNORMALLY FILLING THE SPACE BETWEEN SAID FIRST TERMINAL AND SAID TERMINALMEANS, AND PLUNGER ACTUATING MEANS DISPOSED IN SAID RECESS AXIALLY WITHAND IN A CONTIGUOUSLY ABUTTING RELATIONSHIP AND SUBSTANTIALLY OVERLYINGTHE TUBULAR PORTION AND THE PLUNGER.